This application claims a priority based on German application 199 41 464.5 filed Sep. 1, 1999, and the contents of that application are incorporated herein by reference.
1. Field of the Invention
The present invention relates to inductive position sensors, in particular, to inductive position sensors for motor vehicles
2. Related Art
A known inductive position sensor generates a periodic alternating voltage signal and has, an exciting coil into which this signal is coupled, several receiving coils each of which forms a periodically repeating loop winding structure and whose combined arrangement forms a receiving geometry, an evaluation circuit for evaluating the signals induced in the receiving coils, and a movable inductive coupling element which influences the strength of the inductive coupling between the exciting coil and the receiving coils. Such a position sensor is described in undisclosed patent application DE 199 17 240.
For various applications, where position sensors are used, strict requirements are placed on accuracy and resolution in the acquisition of angles or displacements.
The position sensor disclosed in patent application DE 199 17 240 teaches a position sensor having an accuracy limit at approximately 0.2% accuracy. Using the same sensor principle, an improvement by a factor of 10 is set as an aim. One possible way to increase accuracy is to use the vernier principle that is generally known from measuring technology. For inductive sensors this requires, in principle, two separate sensors constructed with different and independent components.
It is an object of the invention to provide an inductive position sensor, which allows a particularly accurate acquisition of angles or displacements in an uncomplicated and inexpensive way.
The invention achieves this object in that the position sensor exhibits two receiving geometries and two coupling elements, in that the periodicity of the loop winding structures of the receiving coils is different in the two receiving geometries, and in that over the total measuring range of the position sensor the numbers of periodic repetitions in the loop winding structures of the receiving coils of the two receiving geometries exhibit a non-integer ratio in relation to one another.
Advantageously, the constructions and other embodiments of the present invention also permit the absolute acquisition of angles  greater than 360xc2x0 and additionally also acquisition of torque.
The functional principle and embodiments of the inductive position sensor of the present invention are illustrated using drawings, and its method of functioning is explained in more detail. The principles presented for angle sensors are equally applicable to linear sensors.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.